High-Performance, Space-Efficient, Automated Object Locking

The paper studies the impact of several lock manager designs on the overhead imposed to a persistent programming language by automated object locking. Our study reveals that a lock management method based on lock state sharing outperforms more traditional lock management designs. Lock state sharing is a novel lock management method that represents all lock data structures with equal values with a single shared data structure. Sharing the value of locks has numerous benefits: (i) it makes the space consumed by the lock manager small and independent of the number of locks acquired by transactions, (ii) it eliminates the need for expensive book-keeping of locks by transactions, and (iii) it enables the use of memoization techniques for whole locking operations. These advantages add up to make the release of locks practically free, and the processing of over 99% of lock requests between 8 to 14 RISC instructions.